The Main Event, Buffer told the crowd in his familiar voice, would be “12 rounds for the heavyweight championship of the world!”

With his trademark “Let’s get ready to rumble” refrain, Buffer introduced five men who appeared in hooded boxing robes, but they were onstage, not in a ring.

Brothers Jordan and Jonathan Knight, along with Danny Wood, Joey McIntyre and Donnie Wahlberg, collectively known as New Kids on the Block, were back in Las Vegas on Friday to open their 48-stop, two-month tour “The Main Event” through the United States and Canada.

This was no “Fight of the Century,” as the Floyd Mayweather Jr.-Manny Pacquiao fight taking place the next night a few blocks north on Las Vegas Boulevard was billed, but NKOTB delivered some two hours of knockout entertainment to their adoring fans.

On an open stage that spanned about the length of a basketball court in the middle of the arena, NKOTB captivated their audience of predominantly 30- and 40-year-old women, most of whom probably grew up collecting various merchandise from the Boston-born boyband that took the country by storm shortly after it formed in 1984.

Opening-night hiccups were apparent throughout the evening, including Jonathan Knight appearing out of step during several of the highly choreographed numbers. Shirts were misbuttoned and untucked after a costume change, broadcast gratuitously to the audience via beneath-the-stage “quick-change cams.”

Four songs into the set, it looked like a profusely sweating and out-of-breath Wahlberg might not be able to answer the bell for the next round. But the veteran performer and older brother of singer-actor Mark Wahlberg gained a second wind and finished strong.

Good thing, too. His wife, onetime Playboy Playmate, actress and comedienne Jenny McCarthy, was among the crowd opening night of the tour.

Among the show's many highlights:

* McIntyre’s powerful rendition of “Please Don’t Go Girl,” in which he began by sitting on a raised platform at the far north end of the stage and ended on his knees on the south end, then proclaiming, “I’ve been singing this song for 27 (bleeping) years …”

* Jordan Knight, on several numbers including “Didn’t I (Blow Your Mind),” hitting high notes with a still-strong falsetto.

* Wahlberg, accompanying himself on piano and singing “I Need You,” from the group’s second album, “Hangin’ Tough.” “It’s the first time I’ve sung this song live in 30 years,” Wahlberg said.

* Their anthem songs “Step By Step” and “The Right Stuff.” Don’t be fooled: The New Kids on the Block who performed Friday were not the New Kids of the 1980s and '90s. In 1989, then Massachusetts Gov. Michael Dukakis declared a “New Kids on the Block Day” for inspiring youths with pro-school and anti-drug messages.

On Friday, Jordan Knight and McIntyre inspired many in the crowd by stripping off their shirts and gyrating sensually during love songs, and Wahlberg chugged beers during a foray by all of the band members into the audience while they sang “Tonight.”

With a set of more than 20 songs over two hours, New Kids on the Block more than answered the bell and went the distance for their opening night of “The Main Event” tour.

* * *

Opening for New Kids on the Block were St. Louis rapper Nelly and R&B and hip-hop stars TLC, and both delighted those who arrived before the headlining act.

Nelly, dressed in a zippered hoodie with cut-off sleeves and sweatpants, was full of energy for his approximately 40-minute set. Among the standards he performed were his hits “Country Grammar,” “Ride Wit It,” “Dilemma” and a crowd-pleasing “Hot in Herre,” in which the muscle-toned rapper delighted many by stripping off his shirt.

TLC, minus, of course, the dearly departed Lisa “Left-Eye” Lopes, showed that they haven’t lost a step since their 1990s heydays. “Baby, Baby, Baby,” “No Scrubs,” “Red Light Special” and “Diggin on You” had audience members singing and swaying in their seats.

But the highlight of TLC’s set was the finale, “Waterfalls,” the Grammy Award-winning and platinum album-selling group’s biggest hit. Bandmate Rozonda “Chilli” Thomas introduced the tune as “Left Eye’s favorite song,” and a giant video screen above the stage displayed pictures of Left Eye, Chilli and Tionne “T-Boz” Watkins growing up and singing in TLC’s earlier days.

Robin Leach of “Lifestyles of the Rich & Famous” fame has been a journalist for more than 50 years and has spent the past 15 years giving readers the inside scoop on Las Vegas, the world’s premier platinum playground.